Primer compositions for non-stick coatings generally contain a solvent-borne polyamide-imide (PAI) as a bonding resin. Heavy polar aprotic solvents are standardly used as solvents in PAI-based compositions.
In the sense of the present application, polar aprotic solvents are understood to mean solvents which possess a non-zero dipole moment and which are bereft of hydrogen which may form a hydrogen bond. As examples of such polar aprotic solvents, mention can be made especially of NEP (N-ethylpyrrolidone), N-methyl-2-pyrrolidone (NMP), dimethylformamide (DMF), N,N-dimethylacetamide (DMAC), dimethyl sulfoxide (DMSO), etc.
As a bonding resin in primer compositions for non-stick coatings for cookware items, in particular use is frequently made of a solvent-borne polyamide-imide (PAI) resin with 30% dry extract in N-ethylpyrrolidone (NEP) or in N-methylpyrrolidone (NMP), which are solvents generating VOCs and considered as potentially toxic and hazardous.